Dry cleaning apparatus and electrical solution control device



June 14, 1960 1.. L. HENDERSON 2,940,287

DRY CLEANING APPARATUS AND ELECTRICAL SOLUTION CONTROL DEVICE Filed Feb. 1, 1954 2 Sheets-Sheet 1 IN VEN TOR. Z 50AM ED L. HENOERSON BY 7? lChE Y, WA 775, EasfikTon/A NS/VEMVY ATTORNEYS June 14, 1960 L. L. HENDERSON 2,940,287

DRY CLEANING APPARATUS AND ELECTRICAL soumou CONTROL DEVICE Filed Feb. 1, 1954 2 Sheets-Sheet 2 7'0 DRY ClfANl O/1 SOAP TANK FROM WATER TINA MOISTURE cglvrgol SOAP CONTROL mm A56 IN V EN TOR.

BY iP/CHEY, WA rrs, austere/w MSNEN/VY United States Patent M 2,940,287 Patented June 14, 1960 tween the amount of solvent and the amount of soap and the amount of moisture combined with the solvent. There is provided an electronic measuring device which, by determining the hindrance of the-dry cleaning fluid to a :DRY CLEANING APPARATUS AND ELECTRICAL 6 very minute electric current, provides an indication of the SOLUTION CONTROL DEVICE Leonard L. Henderson, 329 Central Parkway,

. Warren, Ohio Filed Feb. 1, 1954, Ser. No. 407,425

8 Claims. (CI. 68-13) proper proportions of solvent, soap and moisture in the .dry cleaning fluid.

An object of the invention is to dry clean garments and the like by means of a solution having a predetermined roptimum proportion of component liquids.

amount of the moisture in the fluid. The arrangement is such that the cleaningfluid constitutes one arm of a vacuum tube bridge which is balanced so as to eliminate the effect of the conductivity of the solvent. As a result, even very small changes in the quantities of soap and moisture may be detected and shown by the resulting Another object of the invention is to maintain an opti- Jnum amount of moisture in a dry cleaning solution.

.Still another object of the invention is to maintain a proper ratio of soap to moisture in a dry cleaning solution.

A further object of the invention is to provide dry" cleaning apparatus in which the proper proportions of soap and moisture are automatically maintained in the cleaning fluid.

A still further object of the invention is to provide a dry cleaning machine in which optimum dry cleaning conditions are automatically maintained for each load of garments.

A still further object of the invention is to provide a highly sensitive and accurate means for determining the electrical condition of a liquid solution having a very high order of resistivity.

In dry cleaning operations such as are ordinarily conducted in commercial dry cleaning establishments, certain conflicting requirements are imposed upon the manager of the establishment. It is highly desirable in dry cleaning garments and the like that a dry cleaning solution be used in which there is an optimum amount of moisture for the amount of soap which is combined with the solvent.

electrical unbalance of the bridge circuit.

In one form of the invention, the condition of the cleaning fluid'is indicated by a visual indicating device so that the operator of the dry cleaning machine may add soap or water until the desired dry cleaning conditions are obtained. Inanother form of the device, the soap and moisture are pumped into the dry cleaning machine, each in turn, until the/optimum proportions of solvent, soap and moisture are obtained.

It is a very important aspect of the invention that the potential applied to the solvent to determine hindrance thereof may be adjusted in accordance with a calibrated scale to correspond to the temperature of the cleaning fluid. This aspect of the invention is particularly importantinasmuch as the most desirable ratios of moisture and soap vary widely with the temperature of the fluid. The invention, together with further objects, features, and advantages thereof will be more clearly understood by reference to the following detailed specification and claims taken in' connection with the accompanying drawings, in

' tain mechanical features thereof;

Fig. 3 is a side view of the connector which may be installed in ordinary commercial dry cleaning machines to enable the practice of the invention;

' Fig. 4 is the end view of the connector of Fig. 3; and

Fig. 5 is a schematic representation of a second embodiment of the invention in which automatic control of the The optimum proportions of moisture, soap and solvent are well known and may be determined from charts which are readily available. However, in the operation of a laundry machine, it is essential that an excess of moisture not be used inasmuch as such an excess of moisture will cause the garment to wrinkle or shrink. Such a result condition of the cleaning fluid is accomplished.

Referring now to Fig. '1, there is shown in representative form a dry cleaning machine 10, an electronic moisture analyzer 11 which is operatively associated with the dry cleaning machine by means of a pick-up'12, and acable leads to substantial expenses by reason of the resulting damage to the garments.

On the other hand, the use of insuflicient moisture in the solution tends to leave the garments in a spotted condition, e.g. moisture is essential to the removal of certain types of water soluble stains. Under such circumstances,

the spots must be removed by hand with the resultant in-' crease in overall cost of cleaning. T

The difliculty has heretofore been in the lack of adequate means whereby the condition of the cleaning fluid" might be determined within the necessary limits of accuracy andwithout expenditure of a great deal of time.

It is the purpose of the invention herein'set forth and described to overcome the above-mentioned difliculties and to provide the operator of the dry cleaning establishment with a continuous measure of the condition of the clean- The invention as herein conceived and embodied is concerned with the operation of a dry cleaning machine in such a way that'the cleaning fluid is maintained in a condition such. that there is a substantially constant ratio be- 13 for connecting the pick-up to the analyzer. The mechanical arrangement of the moisture analyzer 11 with regard tothe dry cleaning machine 10 will, of course, vary widely with the particular circumstances of the installation..

, The dry cleaning machine 10 may be of any well known type having the usual facilities for washing, extracting and solvent recovery, or appropriate separate facilities for the latter operations.

Referring now to Fig. 2, the-apparatus of the invention comprises an electric circuit arrangement including the pick-up 12 which includes a mounting member 14 of insulating material and two electrodes 15 and 16 which extend through the member 14 and project into the interior of the machine. The pick-up 12 is mounted in a wall 17 of the dry cleaning machine so that the electrodes 15 and 16 are immersed in the cleaning fluid within the machine. The electrodes 15 and 16 are, because of the great sensitivity of the mixture analyzer 11, of relatively small dimensions and need have only a small area of contact with the dry cleaning fluid. In one typical embodiment of the pick-up 14, the electrodes were 10 milli- -meters long, 4 millimeters in diameter and spaced 7,rnil1i- I metersv from center-to-center.

mal soap. and dry soap; This mi'eteral's The pick-up 14 is connected to the electrical circuit 19 i of the analyzer 11 by means of the cable 13 which in cludes two insulated conductors 20 and 21 and a shielded means 2.3'and to the ground connection 24 ofthe moisture V analyze'r'll for reasonsmore fully set forth herein.

The moisture analyzerll includes .a soap indicator comprising a meter 25having thescalefthereof calibrated to indicate the soap concentration both interment noriudicates' the amount of moisture for a given percentage of soapin the solvent or soap to solvent ratio. A temperatiirel'indicator comprising a meter 26 having the, scale thereof. Calibrated in terms of temperature. is providedjfor adjusting the electrical circuit to a condition such that .thcfrbsp nse of the circuit corresponds -.to. the temperaturegof the dry cleaning fluid. n I n v Theelectrical circuit 19;c'omprises, 'a; .,yacumn tubev bridge circuit including two vacuum. triodes 2 7" and 28 which are,..for convenience, of the type whichare en-.

. 4 n ing a bias potential to the control grid 50. The bias supply means comprises a voltage divider 57 which is connected to the voltage supply leads 36 and 37 of the power supply 35 and includes the potentiometer 56, a second potentiometer 58, and a dropping resistor 59. The resistor 59 and the potentiometers 56 and 58 and the resistors 52, 54 and 55 are so proportioned that the .grid 50 is'ata lower potential thanthe-cathode -61 of the triode '27.

The potential impressed upon the electrode 16 of the pick-up" 1 4, and-hence the adjustment of the arm 60 of the potentiometer must be determined with reference to the temperature of thesoluti'on 18. The temperature meter 26 which comprises a low current voltmeter is connected to thearm 60 of the potentiometer 56 and to the juncture 62 of the potentiometer 56 with the resistor 59 and is provided With a temperature scale so that the appliedtvoltage is indicated directly in terms of temperaclosed in a common envelope 29. The vacuum triodes .potentiometer)whilethe electrical condition of the fluid 27 and 28 have characteristics which are well known in the art. .Inasmuch as theinventiori is not limited in the practice thereof to the use. of-triodes andmay comprise,

e.g.,triodes orpentodes, the expressioni,electronic discharge devices will be usedin the claims as ageneric nametherefor. v J v Y Y The bridge circuit includes ,as. one branch-thereof the triodes. 27, the plate dropping resistor 30 and resistor 32, together with a portion ofa .balancing potentiometer 34,-

and, as theremaining branch thereoflthe triode 28,.plate,

of the bridge. I V V The bridge is energized by means of a power supply droppingresistonSl, and resistor 33, togetherwith the remair'1ing portion of the potentiometer 314. The triode 27 and resistor30, the triode 28 and the resi'stor 31, the" resistor 32 and the resistor 33. constituteseparate arms ture. The scale of the meter is calibrated indegrees of temperature, according to.-a generally logarithmic scale, inasmuch as the applied voltage changes linearly with the setting of the arm..60 .(the potentiometer 56 is a linear changes logarithmically with-temperature.

The potentiometenSS is. providedso that the manner in whichthe voltage changes withchange in positionof the arm 69. mayflbeatwill. Suchadjustmentsmay -be necessary upon initial. calibration of the. analyzer or when the'solution 18 is itself changed, for example, to use .dilferent additivesso thatrthe reading of the soap indicatorrneter 25 willcorrespond to the actual condition of the solution. In, practi ce,the analyzer must be calibrated for the particular soap being used, and. thisis accomplished by adjusting the potentiometer 58. The-various Potentiometers are-mounted so as to be adjustablefrom the frontpanel of the analyzer 11 during which has the direct current voltage-leads 36 and 37.

thereofjconnected tothe bridge across the principal diagonal'thereof, e.g. to the arm-38 of the,potentiometer 34 I 1 'and'tothe junctureoftheresistorsfiqand 31-. A resistor the varm .60. in accordance. with the temperature of the 39 connected in serieswith-the positive voltage, supply lead 37 serves asastabilizing and isolating resistor.

The control grid 40 ofthe triode 28 is maintained at a suitable-predetermined-bias potential-bya bias network whichaincludes apotentiometer -4-1,,a :gridmesistor 42.,

, andagridcondensor 43; Theg-potentiometer-fl-is conl 1 nected to,the-.negatiye voltage-lead 36 and to the-cathode ;44 and, together. with thceresistors. 33. ar datl e;-.corre-" ysponding"portion-of '-the potenticnn,etel' 34,-Jproduces a};

- voltage drop,-so, that the. arm 45 of the potentiometer 411.

is below the potential ofthe cathode 44 of the triode-28. The bias potential impressed upon the control .grid 40-; is, therefore, determined by'the setting of the-arm 45 of The condensor 43 serves to by 5 pass any rapidly'changin'g'or transient-efiects. I

The control grid of the triode 27 is connected to an).-

electric circuit which,'to'getherwith thecable 13, thef.

the potentiometer 41.

pick-up 12, the cleaning fluid 18 and the'voltage 35,

nitude to thercondition of'the' external circuit,..e.g. as

the operation of the device. Thus, the potentiometer 56 -is mounted below the associated temperature indicator meter 26 and with a knob 63' to permit adjustment of cleaning fluid. The potentiometer 34 is mounted on the frontpanel and isprovided with a knob. 64 so as to vpermitan initial adjustmentiofthe circuit 19- ,as indicatedbythe soap indicatormeter 25. The potentiometer '58 is mounted on the front panel andis provided with ,a knobtiS to permit calibration of themeter 25 and the potentiometer. .56 for different. temperatures. Although notso shown in Fig. 1 thepotentiometer 41 may also e;m.ount d aths, r n P n l o as to P313 11 changes :inthe operating point of thetriodes 27 and 28 during theordinary-use oftheinstrument, to adjustthe .device for use with varioustypesof solutions]. Thegpoten-tiomimposes abias uponithat grid-,which-correspondsin m'ag-.

.eterAI-maycOmprisea rotary tap switch, as isshown in the arrangementof Fig. 5.:- I

, The power supply 35 comprises a power transformer 66 having a primary 67 thereof adapted to be connected ;to a nalternating current supply through a line. switch 68. Thesecondary winding 69 of thetransformer constitutes ;a. highvoltage -Winding for supplying suitable high voltages-to a-rectifier 70. a The pulsating direct current from the'rectifier7tl-is filtered -by acondensor ll which cooperates with the voltage-divider'57-and anisolating v resistor 72.

I have'found that; in-the practice of the invention, it

3 is yery important that the electrical apparatus including the gnaiyzerll, the pick-up -12 'and the cable 13 be completely-sluelded-inorder to eliminatetheeifects of stray capacities: To this end, the analyzer 11; is incorporated the drycleaningimachine andis show'nyin detail in Figs.

"' 3 .and14:li-Asthereshown, the pick-up 12 comprises the two :electrodes" 15.:and 16 which: areflern bedded in and ESUPPDIlfidlbyiflulnmbfi'i Sti -oh insulating:.'l liattaial.v The in a'housingof sheet metal, while the cable 13 includes a nvovehmetallicEsheath'onthe outside thereof. The-pick-up .12 electrically-connects the analyzer, the cableshield and member 80 is .of generally circular cross section and is incorporated in a metallic body member 81 which includes a flange portion 82 having openings 83 for securing the member to the wall of the dry cleaning machine in conductive engagement therewith.

A connector 84 is attached to the end of the cable 13 and comprises a cylindrical body member 85 having an internally threaded portion 86 adapted to engage a similar part 87 of the member 81. The body member 85 is formed of metal and carries an insulating member 88 which, in turn, carries two contacts 89 and 90 which are held in position against the outer ends of the electrode members and 16. The conductors 91 and 92 of the cable 13 are soldered to the contacts 89 and 90 and correspond to the conductors. and 21 of Fig. 2. The sheath 93 is received in a member 94 which is clamped in place and firmly engaged by the body member 85 so as to form an adequate electrical contact with the sheath. While the particular shape of the electrodes is not critical, still it is to be emphasized that it is an important feature of the invention that the probes are of very small physical dimensions. The great sensitivity of the bridge circuit of Fig. 2 enables the use of electrodes of such small size and the advantages of their use will be apparent to those skilled in the .art. In the application of the invention to other purposes, e.g. in laboratories and other analysis work, I contemplate the use of flat electrodes, e.g. 10 millimeters long, 5 millimeters wide and spaced 5 millimeters apart in order to provide a standard reference area which may serve as a basis for subsequent calculations.

In practicing my invention, I fill the dry cleaning machine with a predetermined amount of solvent liquid, either synthetic solvent such as perchlorethylene or a petroleum base solvent. With the moisture indicator 11 properly connected to the pick-up 12 by means of the cable 13 and properly supplied with alternating current, I adjust the knob 63 so that the temperature indicator meter displays a reading corresponding to the temperature of the solvent. I then adjust the knob 64 so that the needle of the indicator meter 25 indicates a zero reading. This adjustment of the knob 64 varies the potentiometer arm 38 so as to bring the bridge to a balance condition, as indicated by the zero reading in the meter, and thereby eliminates the effect of the conductivity of the solvent itself upon the subsequent readings. I then add soap to the solvent while agitating the drum until the meter 25 indicates that a 4% solution has been reached. This determination must, of course, be made upon the norm-a1 soap scale of the meter 25.

For the purposes of calibrating the analyzer, the initial soap percentage must be determined either by quantitive' measure or by titration. When the percentage is determined, the potentiometer 58 is adjusted by knob 65 to indicate the corresponding percentage on the scale of meter 25. The indicator is thus calibrated to give correct percentage reading for this particular brand or type of soap.

Inasmuch as the soap added to the solvent carries a significant amount of moisture, it is necessary in order to insure the accuracy of the subsequent readings to obtain a calibration in terms of percentage of dry soap. I accomplish this calibration by placing a number of garments which have been thoroughly dried into the drum of the dry cleaning machine and, after running the machine for a short period of time, observe the reading on the meter 25 on the dry soap scale thereof. The dry garments tend to absorb the moisture introduced into the solution by the soap so that the moisture plays no effective part in determining the electrical condition of the solvent soap solution. The effect may be observed by the initial solution, it then becomes feasible to determine the exact amount of moisture which must be added for optimum dry cleaning of any given type of garment. Inasmuch as suitable charts are available whereby the optimum quantities of moisture useful in dry cleaning the various types of fabrics for any given soap concentration and'at the various temperatures of the solution, it is necessary only that that optimum quantity be determined and to introduce moisture into the solvent soap mixture in relatively small amounts until the meter 25 indicates a proper percentage of moisture in the resulting solution as measured along the dry soap scale. The moisture is, of course, added after the garments have been introduced into the machine, and while the machine is in operation, so as .to accommodate the tendency of dry garments to absorb substantial quantities of moisture. Care must be taken, of course, where the garments carry a substantial amount of moisture, and, if excessive, a preliminary drying may be necessary in order not to initially carry an excess of moisture into the solution.

Having determined the optimum amount of moisture necessary for the particular cleaning operation and having obtained that proportion of moisture in the cleaning fluid, the cleaning operation may then proceed as desired with the meter 25 providing a continuous indication of the manner in which the ratio of moisture to soap and solvent changes throughout the cleaning operation. It will normal-ly be found that, while the cleaning operation may be initiated with the exact ratio of moisture to soap and solvent desired, but after the operation has proceeded for several minutes, that the needle of the meter 25 will slowly drop back to a much lower reading. Inasmuch as the efliciency of the cleaning operation is greatly re duced under these circumstances, the advantages of the present invention will be readily apparent inasmuch as it is only necessary to add a further small amount of moisture to obtain the optimum proportions of moisture in the solution.

After each load of garments is cleaned, the fluid is drained from the tub of the dry cleaning machine and the cleaning fluid carried by the garments is extracted by spinning the drum of the machine. The solvent recovered from the garments during the extracting process is distilled so that the soap in that portion of the cleaning fluid is lost. In order to maintain the proper component proportions in the cleaning fluid within reasonable limits, I find it desirable to add a stock solution comprising about 25% solvent, 50% moisture and 25% normal soap solutain the proportions of soap and moisture in the dry cleaning machine in response to the measurements brought about by the operation of an electrical bridge circuit corresponding to that shown in Fig. 2. The circuit is such that unbalance of the bridge, such as is indicated by the meter 25 in Fig. 2, causes predetermined quantities of soap and water to be injected into the cleaning machine at predetermined successive intervals of time. More particularly, the apparatus includes an electrical bridge and associated circuits 101, an electrical control apparatus 102, a soap pump 103, a moisture pump 2104, a soap control and a moisture control 106.

The electrical bridge 107 comprises a vacuum tube 108 having two triode sections 109 and 110. Resistors 111 and 112 in the plate circuit of the triodes and resistors H3 and 114 in the cathode circuits thereof constitute parallel arms of the bridge. A balancing potentiometer 115 in the parallel arms functions in the same manner as the corresponding arrangement of Fig. 2.

The soap control 105 comprises a tap switch. 116 and length of time? which the pump is running; .are energizedfrom' the portion'of the power supply 128 includinga lowvolta-ge'winding 130, two half-wave rectihavingresistcrs 143,. .:---between.thesuccessive taps of the switch. A'potentiorneter 148 .serves as-a means 'for calibrating the moisture control circuit. t

-= escape? 1. the. successive taps thereof and corresponding in .function xzto the potentiometer .41 of Fig. 2. A soap indicator .1. meter 1224s connected in the subsidiary diagonal of the bridge .107 and corresponds function to the meter -...25":of Fig. 2.

-. fixed resistors 117, 118,..119and 120connected between 0. w agesupply when the start switch-isclosed. Thexheater element is then. maintained. in .an. energizedricondition .Thestemperature-control includes twopotentiometers .nectedto the pickup 12 by means of a'cableiwhich is connected to .an=utl'et 129. 4/ The soap .pump 103 and the moisture pump 104 are electrically. energized. pumps, each'adaptedto :deliver quantities- 0t fluid whicha-re in direct proportion to the tiers 131 and 132 and a filter comprising a choke 133 and a condensor 134. The negative .terminal of the low voltage supply is grounded at 135.

. Theoperation of the pumps 103 and 104' is controlled by a relay 136 which has the coil 137 thereof connected inaseries circuit across the arms of the bridge between .the anodesof the triodes 109 and 110. The circuit ineludes the relay 136, contacts 138, 139 and 140 of a relay 141 and the moisture control 106.

Themoisture control 106--comprises a tap switch 142 144, 145, 146 and.147 connected The-series circuit which includes the moisture control 106 and the relay 136 is so arranged that, when the bridge becomes unbalanced due. to an "insufliciency of soap or 1123 and 124, a temperature indicator meter 125 and a ii. calibrating.potentiometer 126, all comprising a part of a voltage divider 127 for a' power supply 128 andrsimilar .r.;to the arrangement of Fig. 2. The circuit 101 is conthrough the contacts 159 and 160 :of relay 1aso long .as thatrelayishin an energized condition. The contacts 170 of the relay 169 are. connected from thei.- positive lead 155 to the solenoid 171 ofrelay 152' through normally closedcontac-ts 172 and 173 of the. relay. The solenoid L171, of therelay 152 is, therefore, energized to aoperatev the relay upon the elapse of a predetermined interval after-the start button .153 is closed. Upon operationof the relay 152,the contacts 157 and 158 are opened to-deenergize relay 151 and thereby stop the pump 103,

The pumps 1 1 deenergize the relay 169. and connect themoisture con- :trolz106 series withthe coil 137 of relay 136.

.nected' to the normally closed contact v166 of relay 151 so that,.upon operation "of relay 152 when relay-151 is in an unop erated condition, the solenoid 171 of relay 152 is energized from. the positive lead 155 throughthe con- The;normally open contact 167 of relay 152 .is. contermined intervalof time, the. contacts 178 are .closed to .-co1nplete.a' circuit whlchincludesthe positive lead 155 ofi-the low voltage power supply, the moisture pump 104 and the negative lead 135 of the power supply. The operation of the moisture pump-104 continues so long as -the contacts 149 and150are in a closed condition. When moisture in the cleaning solution,,the relay 136 is operated to energize either the soap pump 103 or the moisture --pump 104.. The operation of those pumps is accomplished :by two contacts 149 and 150. of the relay 136 and two relays 151 and 152 which cause the soap pump and the :-.moisture pump to be successively operated for predetermined intervals of time in order to maintain the proper ratio or" soap to moisture in the. fluids which are added to. the fluid of the machine.

1' .The relay 151-is operatedv by a start switch 153 which is adapted toenergize. the solenoid 15401 the relay from the positive lead 155' of the low voltage supply 156 I through a. series'circuitwhich includes a pair of normally 1 closed. contacts 157 and 158 of the relay 152'. A holding circuit includes the contacts 159 and 160 which serve to maintain the solenoid 154 inan energized condition after the start button 153is released.

' The contact 161201 relay 151is connected tothe contact 150 01 relay 136 while an associated normally open connormals connected to the heater'element 163 of a-tirne delayrelay 164: When, therefore, the contacts 149 and 150 of relay 136 are closed by an unbalanced condition of the bridge-whi e-the relay 151'is operated, a low woltagescircuit through the element 163 is completed so that the contacts 165 areclosed after apredetermined period of time. The contacts 165 are connected in a series circuit whichincludes the positive lead 15501 the low volt- I age power supply; the soap pump 103 and a u ground return to the negative terminal-of the-lower voltage power supplyso that the soap 103 is energized. A second the cleaning fluid has receivedla .sulficientarnount of moisture so that'the bridge is brought back to a balanced or? substantially balanced condition, contacts 149 and 150 are opened, the relay 152 is deenergizcd and contacts 157 and 158 are closed, thus preparing the apparatus for a succeeding cycle of operation If, ior'any reason, an

excessive amount of soap'or moisture is added'to the cleaning fluid, the resulting unbalance ofthe bridge cir- --cuit 107 inthe opposite direction will cause the contacts 149 and 180m close and complete the circuitto an alarm 181.

The relay 136 is a relativelysensitive relay of the order of microamperes and adapted to open andclose l the contacts 149 and 150 upon a current change ofa few microamperes; The extent of unbalance of the bridge J is such that a larger amount, e.g. microamperes is required to produce a mid-scale reading of the meter 122. The variable resistor 1420f the moisture control 106 is, therefore, -required to calibrate the series. circuit so that the relay 136 will be operatedabout-either reference condition of unbalance, e.g. dry soap solution or normal solution.

In operating the apparatus of Fig. 5, I prepare a solution comprising the usual solvent and then add a sufiicient amount of soap to produce a pretermined 4% of normal solution, -e.g. a solution including the moisture carried by the soap. With the soap control set at position a :4 which corresponds 'toa 4% normal solution, I then adnormallyiclosed contact 161 of relay 15 1 isconnected to-a contact 167.01. relay 152 which is also a normally opemcontact; .1f,--theretore, contacts 149 and of andl104is unafiected.

.ilhestartbutton-153-is-connected;to the heater'element 168 of atime-delayrelay --169.so-as-.to-energi z e that gnheaterlelementiromtheposltive leadofi the low volt! just-the calibrating potentiometer 126 until themeter 122 reads-at mid-scale. The temperature control is, of course,

1 set to a position so1that the meter 125 reads a temperature corresponding to the temperature of this solution.

Asuflicient-number of dry garments are then placed in the tub of the machine and the machine isstarted. The

' needle of the meter 122 then moves to the left fro-indicate a'4% dry solution as thegarments absorb the moisture 70 i the relay 136 may becalibrated by closing the contacts 138 carried into the solution by the soap and the circuit of and 139 and adjusting the potentiometer 148 so that the reading of the meter, but close for any:lesser; Ijeading,

e.g. any greater-deflection from the mid point position.

actuating the start button is operated and the pump 7 1 until such time as a 4% deenergizing the relay closure of contacts 174 1-36 and deenergize relay 171.

The operation oftthe apparatus is then initiated by 153 whereupon the relay 151 into the dry cleaning machine. The soap is pumped dry soap solution is reached at 149 and 150 are operated, thus 151 and stopping the pump 103. At the expiration of the interval determined by the time delay relay 169, the relay 152 is operated to deenergize the relay 151, whereupon relay 152 is energized and the moisture pump 104 is started by the relay 177 upon and 175. The moisture pump continues to operate until such time as the cleaning fluid is brought to the condition of relative humidity as determined by the setting of the control 106, and the bridge istagain balancedso as to open the contacts of the relay which time the contacts is connected in the circuit the operation of the moisture -The moisture control 106 of the relay 136 during a pump 104 so that the relay, 136 is not operated while pumping moisture until such time as the balanced condition exists. The resistors 143, 144, 145, 146 and 147 V are of suitable size for determining the various amounts of moisture or degree of humidity desired. The actual setting employed will, of course, depend on the kind of garments .employed For example, position 2 may correspond to white garments; position 3, to silk garments; position 4, to wool garments; and position 5, to raincoats.

The operation of the apparatus is initiated by closing the button 153 for each succeeding load. The apparatus functions to maintain the proper: proportionsiof'soap and moisture withinnarrow limits :and nee'dsto be adjusted only for the different types of articles to be cleaned. that the-specific terminology of.

It isto be, understood the present disclosure is not intended to be restrictive or confining and that various rearrangements of parts and modifications of design maybe resorted to without departing from the scope or, spirit of the invention as herein claimed.

7 What is claimed is:

1. Dry cleaning apparatus comprising the combination a dry cleaning machine, and a pick-up mounted on said machine and having two .relatively small elecof the itrodes adapted to be contacted by the cleaning fluid in the machine, an electrical moisture analyzer and electrical conductors. connecting said moisture analyzer with thesaid pick-up, said analyzer comprising electrical cir- 'cuit means including means for balancing out the effect of the the electrical condition of the fluid after the eifect of the solvent has been balanced out, and means for modifying the response of the said circuit means in accordance with the temperature of the cleaning fluid.

2. Dry cleaning apparatus comprising the combination of 'a dry cleaning machine, a pick-up mounted on the said machine having two relatively small electrodes adapted to be contacted by cleaning fluid in the machine, an electrical moisture analyzerenclosed in a shielded cabinet, and a shielded cable connecting said moisture analyzer with the said pick-up and the cabinet of the analyzer with the housing of the machine, the said analyzer comprising electrical circuit means including means for balancing out the efifect of the solvent of the cleaning fluid, means for determining the electrical condition of the fluid after the effect of the solvent has been balanced out and means for modifying the response of solvent of the cleaning. fluid, means for determining 10 pick-up and the cabinet of the of the dry cleaning machine,

i'the' said' analyzer' comprising electrical circuit means ineluding an electrical bridge having one arm thereof con- 7 cleaning fluid, means for nected to one of the said electrodes and controlled thereby, a meter connected in the subsidiary diagonal of the bridge for indicating unbalance thereof and a potentiometer for balancing out the effect of the solvent of the applying a bias voltage to the remaining one of the electrodes and a meter for indicating the amount of the bias, and means for adjusting the said bias voltage'to set the said temperature indicator to a temperature corresponding to that of the cleaning fluid.

1 4. Apparatus for determining the electrical properties of a solution which comprises the combination of a pickup having two spaced electrodes adapted to be immersed in the solution and an electrical measuring device comprising a balanced electrical bridge having an electronic discharge device in each of two parallel branches thereof, voltage supply means connected across the principal diagonal of the bridge with the positive terminal thereof connected to the anodes of the said discharge devices and the negative terminal thereof to the cathodes of the said discharge devices, a first potentiometer connected in connected to the cathode of one of the said discharge devices and a grid r tentiometer to the control resistor connected from the arm of the said second pogrid of the first discharge device for adjustably determining the bias voltage on the in said control grid,

a second biasing network connected to the arm of the said first'potentio'meter and the control grid or the second one of the said discharge devices andv to one of the said pick-up electrodes, bias supply means:

1 comprising a voltage divider connected across the said which comprises the combination of a balance of the bridge shown by the indicator.

5. Apparatus for determining the proportion of'rnoisture in a dry cleaning fluid including soap and solvent pick-up adapted to be mounted in a dry cleaning machine, the said pick-up including two spaced electrodes adapted to be contacted by the cleaning fluid, a cable having two conductors connected to the electrodes of said pick-up, and an electrical measuring device connected to the remote end of the said cable and comprising an electrical bridge having an electronic discharge device in each the said circuit means in accordance with the temperature 7 adapted to be contacted by cleaning fluid in the machine,

an electrical moisture analyzer enclosed in a shielded cabinet, and a shielded cable connecting said moisture of two parallel branches thereof, voltage supply means connected to the principal diagonal of the bridge formed by the said parallel branches, an indicating device comprising a meter connected in the remaining diagonal of the said bridge, the said meter having a scale calibrated to read soap and moisture concentrations, means for applying an adjustably predetermined bias voltage to a control grid of a first one of said discharge devices, a connection between the control grid of the remaining discharge device and an electrode of said pick-up including one of the said two conductors of the cable, means for applying an adjustably predetermined bias voltage to the remaining one of said pick-up electrodes, a connection between the said bias voltage supply means to the said electrode including the remaining one of the said two conductors, indicating means connected to said last-named supply means includ- 6. Apparatus for; determining theproportionofimoisture in dry cleaning fiuid including soap and solvent which comprises the combinationof a pick-up adapted :to be mounted in a dry cleaning'machine and including two spaced electrodes adapted to becontactedby the cleaning 'fiuid, a cahle having two-conductors connected-to the -.electrodes of the said pick-up :and-.a=' shield conductor adapted-to be connectedtothedry cleaning machine, and an -electrical measuring device connectedLto the-remote end of said cable comprising the electrical bridge having an electronic discharge devicein each of twoparallel branches thereof, voltage snpplymeans connected to the a principal diagonal of the bridge formed byth'e said paral- -lel-branches, an indicating device. comprising a metenconnectedin the remaining diagonal of the said bridge, the

said meterhaving a scale-calibrated tojread soap and rnoisture concentrations, means for applying a predetermined bias voltage to thecontrol grid ofone-ofthe said .Ldischarge dcvices aconnection betweenthe control grid of the remainingdischarge device and .an electrode'of said ,7 pick-up, including oneof the said two conductors of the ,cable, means forgapplying a biasyoltageto the remaining one oi the said pick up electrodes, and means for-ladjust- -in g the said bias voltage,.;a;connection.-between:theisaid b a l ee p-ply means and-th said-electr de in luding the remainingone ofthe said two conductors, an indicating device connected; to the.;l.ast-.named :supplymeans including a meter having a seale.graduated in temperature whereby the voltage applied to the electrode may be set in accordance with the'temperature-jof ;the-fluid,,means for balancing out theeffectpf'the conductivity of-the solvent of the dry cleaning fluid 'comprising agpotentiometer connected. in the said two. branches ;of thehridge andhaving p the. arm thereofconnected to the said-powerzrsupply, and a shield. enclosing .the said electrical .rneasuring device 1 and connected to the said shieldcondmtor; of. the-cable forshielding the. entire app aratus against the; elfect. of

stray capacity efiects.

.7. Apparatus adapted to-beutilizcd with adry :cleaninglmachine including ;a-.pick up ;having two relatively small electrodes adapted. to; be mounted in .the machine and be. contacted by cleaning; fluid therein, .:an electrical moisture analyzer-enclosed; in a shielded cabinet and a shielded .cableconnecting said moisture analyzer.:with thes'a-id pick-up, the said analyzer cemprisingvcircuit 111163118 including anelectrical bridge forbalancing out the .effect of. theinitial normal sol nti on of.:.cleaning fluid,

means .for. determining the .electricalcondition of. the cleaning fluid after the effect of'the normal solution has been balanced out, and means fonmodifying the response ot the said "circuit means. in accordance-with the tem- .1 perature {of the cleaning fluid, anelectrical;-moisture apunrp. adapted to be connectedto-thecloaning machine and toa-Watertank, and electricjcircuit means connected "to the said moisture analyzer and to the said pump for .5 operating the said pump in-response to an unbalance conditiongofthe bridge. 1

v8. Apparatus adapted to be utilized with a dry cleaning machine including a pick-up having two relatively smallelectrodes adapted to. be mounted in the machine and be contacted by cleaning fluid therein, an electrical moisture analyzer enclosed in a shielded cabinet and a shielded cable connecting said moisture analyzer with the said pick-up, the said analyzer comprising electric circuit means including an electrical bridgefor balancing out the effect of the initial normal solution'of cleaning .fluid, means for determining the electrical condition of the cleaning fluid after the effect of the normal solution has been balanced out, and means formodifying the response of the said circuitmeans in accordance with thetemperature of the cleaning fluid, an electrical soap pump adapted to be connectedto the cleaning machine and to a soap tank, an electrical moisture pump adapted to be connected to the cleaning machine and to awater tank, and electric circuit means connected'to the said the said pumps in a predeterrn-ine'd' order in'response to unbalance conditions of the bridge.

References Cited in the file of this patent a 3o NITEDv STATESIPATENTS -:-:l,902,173"a;:Larson Mar. 213 1-933 .Andrus Iet a1.v ;-Mar. 265-1935 Reddish :Dec. 17'; 1935 35.. 2,056,14l.; 1':-Myers -'Sept.' 29,- 1936 -.2,06l,424 w'I-Iutton Nov. 17,1936 2,088,843 Davies Aug."'3;' 1937 2,150,031 Hatfield Man K1939 $2,158,614: Reddish May .16, 1939 40 2,183,142 Mackenzie Dec. 12,1939

2,215,805 Wills Sept.'24, 31940 12,331,799. Pettv Oct. 12., 1943 2,360,523 Simmons Oct. 17, .1944 12,490,634 r Keene Dec. 6, ;.1949 2,540,431 Davis et al Feb:'6; 195'1 2,541,219," -:-Dueringer Feb. 13,1951

2,614,026 :Lascari. Oct. 14,1952 2,621,673 "a-f-Hodgens Dec. 16, 1952 .}-...".2,656,845 wLindsay Oct. 27,1953 59.....;2,7 l5,833.-'5 .Fulton. Aug. 23;- .1955

I FOREIGN PATENTS 5 435,575 Great-Britain Sept.24,1935

OTHER. REFERENCES.

Fulton; ASTMmB-ull. No. 19-2, September 1953, pp. '(TB 153) 63-(TP 158') 68.

i Fulton: Bull. No.-'I-29-2,.Natl. Inst. of. Cleaning and ,Dyeing, Silver.Spring,- Md, Oct. 30, 1952 .(4ppt).

moisture analyzer'and to the saicl'pur'nps for operating 

